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The 

Drexel Institute 

Monographs 



THE ROMANCE OF ENGINEERING 



A LECTURE 

DELIVERED AT THE DREXEL INSTITUTE 
FEBRUARY 16, 1916 

BY 

C. J. TILDEN 

Professor of Civil Engineering 
The Johns Hopkins University 




• • • 

• • • 



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THE ROMANCE OF ENGINEERING 

A LECTURE 

Delivered at the Drexel Institute 
February 16, 1916 

BY 

C. J. TILDEN, 

Professor of Civil Engineering 
The Johns Hopkins University 






m k viz 



THE ROMANCE OF ENGINEERING 



The remarkable and rapid development of modern engi- 
neering has brought many of its more dramatic phases into 
public light. Artists, both with pen and pencil, have made 
use of the opportunities offered, and stories have been writ- 
ten and pictures painted in which the central feature of the 
composition is some engineering creation, either of fact or 
of imagination. Many of Kipling's stories, as for example 
"The Bridge Builders" and ".007," are striking bits of 
romance, with singular truthfulness of detail, in the field of 
modern engineering, and Pennell's sketches of the Panama 
Canal throw a new and most interesting light on that great 
work. 

The subject of this afternoon's talk is not, however, 
modern engineering, except in so far as it is a development, 
just as every human activity must be, out of the inspiration 
and the efforts of men of past ages, but rather a glimpse at 
two or three periods of history of which there is record of 
engineering endeavor. An interesting factor, at once sug- 
gested by these considerations, is that of time, and an effort 
is made to show this time factor in its relation to these 
periods of engineering activity, with especial reference to 
one phase of this activity in the Romance period. Now, an 
engineer prefers to express his ideas, whenever possible, by 
means of a drawing or diagram, and so an attempt has been 
made in the accompanying chart* to show graphically 
this time relation of historical events. 

In this "graphical exhibit" of the time-function time is laid 
off horizontally to scale for a period of over twenty- three 
hundred years — from the fourth century B.C. to the pres- 



* The basic idea of this chart was obtained from Clemens Herschel's interesting and 
scholarly edition of Frontinus' "Two Books on the Water Supply of the City of Rome." 
In order to show certain time-relations of the Roman period Mr. Herschel developed this 
scheme of making a scale drawing, so to speak, of the time-function. The chart shown 
herewith is simply an adaptation and extension of the same idea to a longer period. 



4 THE DREXEL INSTITUTE MONOGRAPHS 

ent — the main divisions being marked as centuries while the 
smaller sub-divisions show intervals of a decade. The 
vertical sub-divisions, covering ninety years to the same scale 
as the horizontal, represent similarly the span of human life, 
so that the lifetime of an individual is shown as a straight 
inclined line, at forty-five degrees to horizontal (or vertical) 
whose ordinate, or height above the base-line, at any point 
shows the age of the individual while the corresponding 
abscissa (horizontal distance) gives century and year of the 
Christian era. Thus Archimedes whose life spanned the 
greater part of the third century before Christ, is shown 
graphically, so to speak, by the inclined line running from 
287 B.C. to 212 B.C. and reaching a height (age) of 75 
years. In general, the names have been picked out rather 
at random, many of them being entered on the drawing 
merely to perform the function of convenient and easily 
recognized mile-posts, while a few are those of men who 
have had an important part, each in his day, in the develop- 
ment of engineering. 

It is worth while to note the two lines at the right of the 
lowest line of the diagram representing respectively the first 
and the twenty-eighth presidents of the United States. 
The fact that the time-function of our national life is in- 
cluded between these lines gives, perhaps, a better idea of 
the scale of the diagram than anything else. 

In some cases it has not been possible to find the dates of 
birth and death, and the inclined lines must then be omitted, 
the name alone appearing as near to its proper place, 
chronologically, as it is possible to put it. Of Hippodamus, 
for example, a Greek architect of Miletus, little is known 
except that he lived some four or five hundred years before 
Christ, and planned and built cities. Dinocrates, "a great 
and original Greek architect" of a little later period, was a 
contemporary of Alexander the Great, for whom he also 
built cities, but the date of his birth and death are not 
known. There is similar lack of exact knowledge concern- 
ing Vitruvius, but he appears to have lived in the time of 
Augustus and wrote a treatise on Architecture, (which at 



THE DREXEL INSTITUTE MONOGRAPHS 5 

that time included also all branches of Engineering, both 
military and civil), which was destined later to exert a 
strong influence on the character and development of the 
art of building. 

Certain other time phases of this treatise of Vitruvius are 
further shown by some of the entries on the chart. The De 
Architectura Libri Decern* was written, probably, just about 
the beginning of our era, but the oldest known manuscript 
dates from the tenth century or thereabouts. For another 
five hundred years this manuscript lay practically unknown 
until its discovery at the Monastery of St. Gall. It is seen 
that this discovery took place just as the interesting period 
known as the Renaissance was beginning, and it is easy to 
conceive with what interest such a voice from the past would 
be received. Vitruvius is didactic and tedious in places, 
but he presents his views systematically and with emphasis, 
and his treatise was pretty generally accepted by the archi- 
tects of the Renaissance as an unquestioned authority. 

To the modern engineer there is much of interest in the 
writings of Vitruvius. He divides the field of Architecture 
into three main divisions as follows: 

1. The Art of Building. 

a. The construction of fortified towns and of works for 
general use in public places — 

I. For defensive purposes — the planning of walls, 
towers and gates, permanent devices for re- 
sistance against hostile attacks. 
II. For religious purposes — the erection of fanes 
and temples to the immortal gods. 
III. For utilitarian purposes — the provision of 
meeting places for public use, such as harbors, 
markets, colonnades, baths, theatres, prome- 
nades, and all similar arrangements. 

b. The putting up of structures for private individuals. 



*The latest English translation of the "De Architectura" is by Professors Morgan 
and Howard of Harvard University, with drawings prepared under the direction of Pro- 
fessor Warren. It was published in 1914. 



6 THE DREXEL INSTITUTE MONOGRAPHS 

2. The Making of Time-pieces. (Sundials, water clocks, 

etc.) 

3. The Construction of Machinery — 

a. Civil — water wheels, screw pumps, hodometers, etc. 

b. Military— balistas,catapults,rams,siegemachines,etc. 

In the light of modern developments of engineering this 
seems a fairly comprehensive group of subjects. Some of the 
specific chapters in Vitruvius are, however, much more clear- 
ly related to present day ideas. The details which he gives 
of construction in wood and masonry, and especially in 
brick, are full and complete, and many times quite in accord 
with modern practice. His description of the tests that 
should be applied to sand to determine its fitness for use in 
mortar might almost be taken directly from masonry speci- 
fications of to-day, and the use of the inverted siphon, 
rediscovered and invented again by hydraulic engineers of 
not very many years ago, seems to have been pretty well 
understood by the Roman builders of that day. 

One paragraph in Vitruvius is worth quoting in full in 
view of the increased importance within the last few years 
of the valuation of engineering structures, and the wide- 
spread discussion of the principles underlying valuation 
work. The following is from Chapter VIII of Book II: 

"No walls made of rubble and finished with delicate 
beauty — no such walls can escape ruin as time goes on. 
Hence, when arbitrators are chosen to set a valuation on 
party walls, they do not value them at what they cost to 
build, but look up the written contract in each case and then, 
after deducting from the cost one-eightieth for each year 
that the wall has been standing, decide that the remainder 
is the sum to be paid. They thus in effect pronounce that 
such walls cannot last more than eighty years. 

"In the case of brick walls, however, no deduction is made 
provided they are still standing plumb, but they are always 
valued at what they cost to build." 

Here is an interesting and simple "straight-line" formula 
for depreciation, as well as a highly common-sense view to 



THE DREXEL INSTITUTE MONOGRAPHS 7 

take of brick walls that still "stand plumb," which should 
receive the careful consideration of valuation engineers. 

Another record of engineering work of the time of Im- 
perial Rome is that of Sextus Julius Frontinus, for many 
years Water Commissioner of the city, an important office 
which he seems to have filled with honor and a fine public 
spirit. Frontinus* work consists of two books, or short essays 
(for the total in English translation amounts to less than 
twenty thousand words), describing the various aqueducts 
which brought water into the city. There is more genuine 
thought to this work than is shown in Vitruvius; apparently 
Frontinus took himself less seriously and his work more 
seriously than the earlier engineer. 

In the introduction he speaks of the high office which had 
just been conferred upon him by the emperor, and expresses 
his gratification at the honor and his realization of its im- 
portance to the health and welfare of the city. He then 
reviews briefly the history of the Roman water supply from 
the foundation of the city and describes the various aque- 
ducts, and the Consuls and others who were responsible for 
building them. He is immensely proud of these great works 
and after several pages of description he asks the question, 
"Will anyone compare the idle pyramids or those other use- 
less though much renowned works of the Greeks with these 
aqueducts?" He then tells how in accepting the office of 
Water Commissioner from the emperor he felt it his duty 
to examine carefully all the channels, in order to determine 
what amounts of water they should bring into the city and 
which ones were failing in their duty. 

Frontinus evidently spent much time and thought on this 
question of measuring the flow of water and he describes 
in detail the unit of measure which he called the quinaria. 
The quinaria, however, was merely a spout with a given 
cross-sectional area — a circular orifice with a diameter a 
little less than one inch in modern measure. Frontinus 
gives the credit for this unit to Vitruvius, and spends a good 
deal of time describing the pipes and how they were used. 
But he fails to recognize the fact that a one-inch diameter 



8 THE DREXEL INSTITUTE MONOGRAPHS 

pipe will discharge varying quantities of water depending 
upon the depth of the water above the opening. He tried 
hard to check up the quantities of water flowing to the city 
through the various aqueducts, and calls attention to two 
evils with regard to the distribution of water, first, the dis- 
honesty of those who surreptitiously tapped either the 
aqueducts or distributing pipes, and secondly, the special 
favors which were often granted to powerful or influential 
individuals. His organization for the repair and the 
maintenance of the aqueducts is also described, and he dis- 
cusses the various maintenance difficulties such as the forma- 
tion of incrustations from the very hard water from most of 
these springs, the destruction of the concrete lining resulting 
in leaks, etc., and also states the rule that only one aqueduct 
should be repaired at a time in order that the continuity of 
the supply to the city should not be broken. It was a rule 
of the Senate that spaces should be kept clear and unoc- 
cupied for fifteen feet on each side of the springs, arches and 
walls of the aqueducts in order to facilitate keeping them 
clean and in proper repair. 

In fact, the impression one gets from reading Frontinus' 
highly entertaining little book is that the water supply of 
Rome was in general quite as well organized as that of a 
modern city, and that honest city officials had much the 
same difficulties to contend with, both from conscienceless 
individuals and from those who abused political power and 
influence, as are found to-day. Still more interesting, per- 
haps, is the picture that one gets of the author of the book, 
Frontinus himself. He was evidently a man of influence and 
power, trusted by the emperor, and with a long record of dis- 
tinguished service to the state. He wrote several other 
works in addition to the "De Aquis," one on stratagems of 
war, a treatise on surveying, one on boundaries, roads, etc., 
and a work on Roman colonies. He had earned an excellent 
reputation as a soldier and the post of water commissioner 
was apparently the culmination of his career. 

Until 1899 there was no English translation of Frontinus* 
"De Aquis." At that time Mr. Clemens Herschel, the well- 



THE DREXEL INSTITUTE MONOGRAPHS 9 

known hydraulic engineer, in New York, published his 
delightful book in which he gives not only a translation, but 
also a photographic reproduction of the oldest manuscript, 
the "Montecassino Codex," as he calls it, of Frontinus' 
work. This manuscript is a precious document of 23 
pages of parchment written in the cramped, uncial writing 
of the middle ages, and kept in the library of the monastery 
of Montecassino in Italy. In his detailed comment on the 
essay Mr. Herschel makes one point which is particularly 
interesting as coming from a scientific scholar who has given 
so much thought to the whole subject. This is in reference 
to the popular idea that the Roman engineers believed that 
the conduits which brought the water into the city should 
be kept level, or with only a slight fall, to allow the water to 
flow from the source of supply to the point of distribution 
within the city. Mr. Herschel contends with some emphasis 
that people who were capable of building and maintaining 
such an elaborate and beautiful system of water supply 
must know the fundamental principle of the syphon. "Let 
us stamp out if we can," he says, "the shallow idea that those 
men did not know that water would rise as high in the pipe 
as the source from which it came." He cites Vitruvius who, 
as mentioned above, tells how to build inverted syphons, 
saying that it could be done with lead pipe or drawn pipe, 
and also quotes Pliny the Elder, to the effect that "water 
climbs to the height of its own origin." Then he goes on to 
say that it is not difficult to find the reason why the Romans 
seldom used the principle of the inverted syphon. "They 
did simply what every engineer does at the present day. 
... At every point of operation a good engineer will use 
to the best advantage possible, the materials and facilities 
for his work found at hand for the time being; and this is 
what the Romans did. Not having cast iron pipes, they 
builded as could best be done without them, and were we 
deprived of cast iron, wrought iron, and steel pipes, we should 
to-day be obliged to build water works pretty much as they 
built them." 

Mr. Herschel comments amusingly on the utter impossibil- 



io THE DREXEL INSTITUTE MONOGRAPHS 

ity of following Frontinus , arithmetical computations, in the 
chapter in which the honest old commissioner tries to figure 
out water quantities, etc. It certainly appears impossible 
to reach his conclusions by any of the accepted rules of 
arithmetic. This is not surprising, however, when it is 
remembered that the earliest record that we have of what 
Frontinus wrote was penned fully noo years after he wrote 
it. The Montecassino manuscript dates from about the 
1 2th century, and although there is indication that it was 
copied from a manuscript of possibly the fourth century, 
(or of the period from the fourth to the eighth centuries) 
there is, of course, no telling how many hands or how many 
minds had been concerned with it since Frontinus first 
wrote it. 

Returning once more to the chart it is seen that little of i 
engineering interest can be recorded in the long period of the 
Dark Age, and the early Middle Ages. Constantine and St. 
Augustine mark the practical ending of Rome's power, then , 
follow centuries of barrenness and ignorance lightened by the 
brilliant but comparatively brief power of Charlemagne. 
Alfred the Great in England, and Hugh Capet, the first 
elective king of the Franks, are names which stand out as 
exponents of progress and the beginnings of political freedom 
and industrial effort. 

Near the end of the eleventh century there began that 
singular outburst of emotional religious enthusiasm which 
crystallized in the Crusades. Fired by the preaching of 
St. Bernard, Peter the Hermit, and other enthusiasts, 
countless thousands entered on the holy quest of recovering 
the sepulchre of Christ from the hands of the infidels. 
Roads were bad, bridges, fords and ferries few, and travel 
accordingly dangerous. To build roads and bridges, to 
maintain ferries at suitable points on rivers, or in any other 
manner to help and protect pilgrims on their way, naturally 
became praiseworthy and pious tasks, "useful to posterity 
and consequently pleasing to God." A religious or semi- 
religious confraternity known as the "Brothers of the 
Bridge" {Fratres Pontis or Fratres Pontijices) came into 



THE DREXEL INSTITUTE MONOGRAPHS n 

existence about 1177, the shepherd boy, B6nezet, afterwards 
canonized, being generally looked upon as the founder of 
the order in France. The principal source of information 
concerning this religious order is a small book published in 
Paris nearly a century ago — Recherches Historiques sur les 
Congregations Hospitalieres des Freres Pontifes y by Henri 
Gr£goire, at one time Bishop of Blois. Brief references may 
be found in various encyclopedias and other general works, 
and rather full and extended descriptive accounts of the 
bridges appear in Viollet-le-Duc's Dictionnaire Raisonee de 
V Architecture Franqaise du Moyen Age. Definite and 
precise information about the brotherhood — or brother- 
hoods, for there were undoubtedly several organizations 
more or less closely bound to some central authority — 
is, however, hard to gather, for much of it seems to rest on 
legends which do not stand the test of too close analysis. 
But, after all, what does it matter if it appears that the shep- 
herd lad, Benezet, was only thirteen years old when he 
began the construction of the remarkable bridge at Avignon? 
He was divinely inspired to build it, and surely a divine 
inspiration more than overbalances mere youthfulness. 

This bridge at Avignon, still known as the bridge of Saint 
B6n6zet, was built in the decade from ii78to 1188. Bene- 
zet died before it was finished and is buried in the little 
chapel which surmounts one of the piers. The bridge is 
now in ruins, only four arch spans remaining of the original 
eighteen, but these show many interesting details of con- 
struction. The structure was originally over a half mile in 
length with a width at the roadway, including the thickness 
of the parapet, of about sixteen feet. The piers between 
the arches are exceedingly heavy in order to resist the masses 
of floating ice which come down the Rhone in the early 
spring. The current of the Rhone is rapid at this point 
and the river divides into two branches, one of them much 
wider than the other, so that the bridge itself crossed the 
intervening island. The arches had a clear span varying 
from twenty to twenty-five metres — roughly, sixty-five to 
eighty feet, while the piers were about thirty feet thick with 



12 THE DREXEL INSTITUTE MONOGRAPHS 

a total length up and down the river, of nearly one hundred 
feet. 

One interesting point in regard to the arches is that the 
trace of the soffit is neither a parabola nor a semi-circle, 
but a curve which lies, roughly, midway between the two. 
The circular arc would have been perhaps the most natural 
form to use, as it is in many ways — or was at that time, at 
least — the easiest one to lay out either on a drawing or in 
the field. The parabolic form, however, is probably a 
better curve theoretically, and it is interesting to note that 
in some manner, although the theory of structures as known 
to-day had no existence whatever at that time, these builders 
were able to closely approximate the theoretically perfect 
curve. Each arch span is made up of four independent 
ribs, placed close together "in parallel," so to speak, but 
not tied together or bonded in any way. Each rib is a true 
voussoir or block-work arch, the arch-stones having a depth 
of about sixteen inches with closely fitting joints laid in 
excellent mortar. Although the individual ribs are not 
bonded, the heavy mass of masonry which surmounts and 
loads them ties the entire structure together solidly and 
sufficiently. The work is done with rather small stones, 
cut and fitted together with considerable care. 

Viollet-le-Duc, from whose fascinating work on the 
Architecture of the Middle Ages the above details with 
regard to the bridge of St. Benezet are taken, comments with 
gross materialism on certain practices of the builders of those 
days. "There are many romance constructions which show 
on the part of the architect a complete lack of foresight. 
A structure, for example, was evidently begun with a vague 
idea of finishing it after a certain manner, which, however, 
stopped half way, the constructor not knowing how to solve 
the problems with which he was confronted; another build- 
ing could not be finished save by using means evidently not 
thought of in the original plan. One realizes that the early 
mediaeval architects built from day to day, trusting to 
inspiration, to chance or to circumstances, perhaps even 
counting on a miracle to bring their work to a satisfactory 



THE DREXEL INSTITUTE MONOGRAPHS 13 

conclusion. The legends connected with some great build- 
ings (and the buildings themselves are there to show us the 
difficulties of the architects) are full of dreams during 
which these architects saw some saint taking the trouble 
to show them how they should build their vaults or support 
their columns; something which did not always keep the 
structures from falling down after they were finished, for 
faith alone does not suffice for building." 

A few miles up the river from Avignon is the bridge of 
Saint Esprit, said by Viollet-le-Duc to be the last important 
work of the Brothers of the Bridge. This comprises twenty- 
two arches, each a full centered span, the other details being 
not unlike those of the Avignon bridge. Thirty years were 
occupied in building the bridge of Saint Esprit, and after its 
completion the brotherhood seems to have fallen into a slow 
decadence which led at last, about the middle of the four- 
teenth century, to its dissolution. The final breaking-up 
came largely as a result of the corruption which so often 
follows increase of power and wealth, for the order had fallen 
away from the strict rules of poverty and humility which 
characterized the earlier brothers, and which had such strik- 
ing exemplification in the contemporary followers of Saint 
Francis of Assisi. 

The [Brothers of the Bridge came into being to meet a 
specific need of the time. Perhaps it is natural enough that, 
after the need had passed away, the brotherhood should die 
a natural death. It is a pity, however, that the history of 
its last years should be marred by cupidity and ill-used 
power. In order to give greater emphasis to the good they 
did, it is worth while to quote here the words (in transla- 
tion) in which Bishop Gr6goire sums up the high aims and 
unselfish activities of the Brotherhood at its best: "To give 
lodging to travelers, to care for them if they were ill, to help 
them across rivers, to go with them and lend a strong and 
brave hand against the attacks of the brigand troops often 
found in those lawless times, to construct bridges, ferries, 
dams, roads, such were the constant labors of the Brothers 
of the Bridge who in that way helped the development of 



i 4 THE DREXEL INSTITUTE MONOGRAPHS 

some branches of industry and were in many ways the re- 
storers of architecture and commerce." 

Once more we must skip rapidly along the time-chart, 
this time, however, over centuries full of the charm of great 
names of artists, reformers, builders, and writers. The 
period of the Renaissance, and the later period up to the 
French Revolution and the beginnings of our own national 
existence, are full of the more intense and vital interest of 
comparatively recent history. There is, however, only one 
other book, a record of a great achievement, which will be 
commended this afternoon to the attention of the student of 
engineering history. This is Robert Stevenson's story of 
the building of the Bell Rock lighthouse, as told by his 
grandson, Robert Louis Stevenson, in his essay on "A 
Family of Engineers." It is hard to find its equal as a tale , 
of remarkable accomplishment in spite of almost insur- 
mountable difficulties. The lighthouse was built on the 
dangerous Inchcape Rock — made famous in Southey's , 
poem — a ragged ledge off the east coast of Scotland some 
twelve miles from the mainland. The rock is bare only 
at certain stages of the tide, so that the difficulties of carry- 
ing on building operations, which had to be suspended 
entirely during the winter months, were unusually great. 
The record of the work, which extended over five consecutive 
summer seasons, is in the form of a diary kept by the elder 
Stevenson and edited by his grandson. The engineer 
Stevenson was a careful and painstaking recorder of events 
and processes, as well as an energetic and able designer and 
builder, and he sets forth both successes and failures in a 
frank and exact manner. 

One discussion in Stevenson's book, which he treats at 
some length, concerns the matter of Sunday work, and makes 
rather interesting reading in this day when so little attention 
is paid to that question. In the earlier stages of the Bell 
Rock project, especially during the preparation of the 
surface of the ledge to receive the artificial foundation, it 
was possible to work but a short time — sometimes hardly 
more than an hour or two — twice each day. These working 



THE DREXEL INSTITUTE MONOGRAPHS 15 

periods were, of course, entirely dependent upon the tide, 
and the question of working on Sunday, in order to make the 
most of the limited opportunities, was bound to be raised. 
It meant a severe struggle with the stern Scotch conscience. 
The pros and cons were argued — or better, perhaps, de- 
liberated — in sessions at which the entire little group of 
workmen were present, and every phase of the question was 
critically examined. The idea which finally prevailed was 
that the work on which they were engaged was a "work of 
humanity and necessity," and that there could be, therefore, 
no offense in Sunday labor. It was, however, left to each 
individual workman to do as he thought right, and all but 
two of the number agreed to work Sunday whenever the tide 
permitted. 

It is possibly needless to suggest in conclusion the idea 
which is uppermost in these activities of three such widely 
separated periods. Differing greatly as they do in the nature 
of their work and their manner of doing it, the dominant 
note is still the spirit of service, the recognition of a public 
need and a striving to fill it. The sturdy Scotch colleagues 
of Stevenson, who subordinated their strict ideas of Sabbath 
observance to a dangerous work of necessity, the Brothers 
of the Middle Ages who expressed their religious enthusiasm 
in lasting creations of stone and mortar for the good of their 
fellowmen, and the faithful and energetic water commissioner 
of Rome, whose chief desire was to keep the city well sup- 
plied — all were inspired by the same ideal of useful, creative 
work. It is the ideal that dominates the work of the engi- 
neering profession to-day, and must so continue if the pro- 
fession is to live. 

The Brothers of the Bridge sometimes marked their 
bridges with the following couplet expressive of their belief 
in creative labor for the good of others. Although coming 
from an age when religious feeling was a simpler and more 
universal companion of daily life than it is to-day, it has a 
lesson for all time, and furthermore throws an interesting 
side-light on the character of those early workers. It 
is a rare expression of a simple and unselfish creed growing 



16 THE DREXEL INSTITUTE MONOGRAPHS 

out of inspired work. Who the writer was we are not told, 
but his hand must have been that of a true master and he 
himself a loyal "Brother of the Bridge" — 

"Straverunt alii nobis, nos posteritati, 
Omnibus ut Christus stravit ad astra viam."* 



*Those who have gone before us 

Have paved the way. 
So must we build new roads 

For those who come; 
Even as Christ himself has paved for all 

The Way to Life. 



LIBRARY OF CONGRESS 



028 106 700 ft 



FftANKlIN MINTINfl 0*.| fMH-A. 



